William entered the Boy's Dorm with the egg he had named Mischievous inside the pocket of his robes. He didn't realize that it was so chilly outside, for when he took Mischievous out of his pocket he noticed that it was really cold. He knew that it wasn't good for Mischievous to get too hot or too cold, so he decided he needed to warm the egg up a little.

William took his wand out of his other pocket, set Mischievous down on his bed and then pointed his wand directly at the metal egg. "Argentum Calidus," he said, taking care to pronounce the words carefully. At the same time he was saying the spell he used a swishing motion with his wands, the same one the Charms professor had demonstrated in class, and then followed by tapping his wand lightly on Mischievous.

Within a few minutes, he touched the egg and saw that the temperature had risen to an acceptable level. "Now you're nice and comfy, Mischievous," William said, patting the egg lightly. "Get a good sleep."

William placed the egg on a pillow next to the bed. He saw that Mischievous was already trying to skip away and scolded the egg gently. "Lie down and go to sleep, Mischievous," he told the little metal egg. "We don't want either one of us to get in trouble for roaming about these halls at night!"

Finally the egg was still, and William sighed softly. Taking care of Mischievous was proving to be tougher than he thought. Mischievous' name was proven to be more apt than he had ever thought.